Insulated ducts and insulated ductworks

ABSTRACT

A duct for use in an HVAC system is provided. The duct including an outer tube. The duct also including an inner tube capable of conveying forced air. The inner tube extending within the outer tube and along the outer tube. The duct further including a plurality of support elements spanning between the outer tube and the inner tube. The elements extending along the inner tube and the outer tube. The elements defining a plurality of channels between the outer tube and the inner tube. The outer tube, the inner tube and the elements are unitary.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 61/650,583, filed on May 23, 2012, which is hereinincorporated by reference in its entirety for all purposes.

TECHNICAL FIELD

Generally, the present disclosure relates to heating, ventilation andair conditioning (HVAC) ducts. More particularly, the present disclosurerelates to HVAC duct insulation.

BACKGROUND

In the present disclosure, where a document, an act and/or an item ofknowledge is referred to and/or discussed, whether directly and/orindirectly, then this reference and/or discussion is not an admissionthat the document, the act and/or the item of knowledge and/or anycombination thereof was at the priority date, publicly available, knownto the public, part of common general knowledge and/or otherwiseconstitutes prior art under the applicable statutory provisions and/oris known to be relevant to any attempt to solve any problem with whichthe present disclosure is concerned.

HVAC systems are generally used to control various aspects of indoor airenvironment. In order to conduct air within the HVAC system, a ductworkis typically used. The ductwork usually includes a plurality ofinterconnected sectioned ducts. A common type of such duct is fabricatedfrom a single-walled sheet metal formed into a plurality of conduitshaving rectangular or circular cross-sections.

Many jurisdictions have legal codes, such as building codes, regulatingconstruction and maintenance of buildings located within thejurisdictions. In order to promote efficient energy use, some of suchcodes require the ductwork to be insulated at least during buildingconstruction. Such insulation limits thermal energy transfer between theair within the ductwork and the air outside the ductwork.

A typical ductwork insulation process involves wrapping fiberglassinsulation jacket around many, if not all, ducts within the ductwork andtaping the seams to seal. The HVAC system is then pressure tested toensure absence of air leaks within the ductwork. Although suchinsulation method is relatively effective, the method can be timeconsuming and costly to implement. A more efficient technology forinsulating ducts and ductworks is thus desired.

While certain aspects of conventional technologies have been discussedto facilitate the present disclosure, no technical aspects aredisclaimed. The claims may encompass one and/or more of the conventionaltechnical aspects discussed herein.

BRIEF SUMMARY

The present disclosure addresses at least one of the above. However, thepresent disclosure may prove useful in addressing other problems and/ordeficiencies in a number of technical areas. Therefore, the claims, asrecited below, should not be construed as necessarily limited toaddressing any of the particular problems and/or deficiencies discussedherein.

According to an example embodiment of the present disclosure a duct foruse in an HVAC system is provided. The duct including an outer tube. Theduct also including an inner tube capable of conveying forced air. Theinner tube extending within the outer tube and along the outer tube. Theduct further including a plurality of support elements spanning betweenthe outer tube and the inner tube. The elements extending along theinner tube and the outer tube. The elements defining a plurality ofchannels between the outer tube and the inner tube. The outer tube, theinner tube and the elements are unitary.

According to another example embodiment of the present disclosure a ductfor use in an HVAC system is provided. The duct including an outer tubehaving an interior space and a first open end. The duct also includingan inner tube capable of conveying forced air. The inner tube extendingwithin the interior space and along the outer tube. The inner tubehaving a second open end in proximity of the first end. The duct furtherincluding a thermally insulating layer partially filling the interiorspace. The layer recessed with respect to the first open end and thesecond open end.

According to yet another example embodiment of the present disclosure aductwork for use in an HVAC system is provided. The ductwork including afirst duct including a first outer tube and a first inner tube capableof conveying forced air. The first inner tube extending within the firstouter tube and along the first outer tube. The first duct including aplurality of support elements spanning between the first outer tube andthe first inner tube. The elements extending along the first inner tubeand the first outer tube. The elements defining a plurality of channelsbetween the first outer tube and the first inner tube. The channels arefilled with a plurality of thermally insulating layers. The ductworkalso including a second duct including a second outer tube having aninterior space and a first open end. The second duct including a secondinner tube capable of conveying the forced air. The second inner tubeextending within the interior space and along the second outer tube. Thesecond inner tube having a second open end in proximity of the firstend. The second duct including a thermally insulating layer partiallyfilling the interior space. The layer recessed with respect to the firstopen end and the second open end. The second outer tube wider than thefirst outer tube. The first outer tube, the first inner tube and theelements are unitary. The layers are in contact with the layer. Thefirst inner tube in fluid communication with the second inner tube. Thefirst outer tube partially within the interior space.

Additional features and advantages are realized through the techniquesof the present disclosure. The present disclosure may be embodied in theform illustrated in the accompanying drawings. Attention is called tothe fact, however, that the drawings are illustrative. Variations arecontemplated as being part of the disclosure, limited only by the scopeof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate example embodiments of the presentdisclosure. Such drawings are not to be construed as necessarilylimiting the disclosure. Like numbers can refer to like elementsthroughout.

FIG. 1 shows an example embodiment of an insulated duct according to thepresent disclosure.

FIG. 2 shows another example embodiment of an insulated duct accordingto the present disclosure.

FIG. 3 shows an example embodiment of an intermediate duct before usewith a pair of insulated ducts according to the present disclosure.

FIG. 4 shows an example embodiment of a ductwork employing anintermediate duct according to the present disclosure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present disclosure will now be described more fully with referenceto the accompanying drawings, in which example embodiments of thepresent disclosure are shown. The present disclosure may, however, beembodied in many different forms and should not be construed asnecessarily being limited to the embodiments set forth herein. Rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey the concept of the disclosure tothose skilled in the art. Also, features described with respect tocertain embodiments may be combined in various other embodiments.Different aspects and elements of the embodiments may be combined in asimilar manner. The disclosed embodiments may individually orcollectively be components of a larger system.

Any verbs as used herein can imply direct or indirect, full or partial,action or inaction. For example, when an element is referred to as being“on,” “connected” or “coupled” to another element, then the element canbe directly connected or coupled to the other element or interveningelements may be present. In contrast, when an element is referred to asbeing “directly connected” or “directly coupled” to another element,there are no intervening elements present.

Although the terms “first,” “second,” etc. may be used herein todescribe various elements, components, regions, layers and/or sections,these elements, components, regions, layers and/or sections should notbe necessarily limited by these terms. These terms are only used todistinguish one element, component, region, layer or section fromanother element, component, region, layer or section. Thus, a firstelement, component, region, layer or section discussed below could betermed a second element, component, region, layer or section withoutdeparting from the teachings of the present disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be necessarily limiting of thepresent disclosure. As used herein, the singular forms “a,” “an” and“the” are intended to include the plural forms as well, unless thecontext clearly indicates otherwise. The terms “comprises,” “includes”and/or “comprising,” “including” when used in the present disclosure,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence and/oraddition of one and/or more other features, integers, steps, operations,elements, components, and/or groups thereof.

Example embodiments of the present disclosure are described herein withreference to illustrations of idealized embodiments (and intermediatestructures) of the present disclosure. As such, variations from theshapes of the illustrations as a result, for example, of manufacturingtechniques and/or tolerances, are to be expected. Thus, the exampleembodiments of the present disclosure should not be construed asnecessarily limited to the particular shapes of regions illustratedherein, but are to include deviations in shapes that result, forexample, from manufacturing. For example, a region illustrated ordescribed as flat may, typically, have rough and/or nonlinear features.Moreover, sharp angles that are illustrated may be rounded. Thus, theregions illustrated in the figures are schematic in nature and theirshapes are not intended to illustrate the precise shape of a region andare not intended to necessarily limit the scope of the present claims.Any and/or all components and/or materials can be formed from a same,structurally continuous piece and/or be separately manufactured and/orconnected.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which the present disclosure belongs.The terms, such as those defined in commonly used dictionaries, shouldbe interpreted as having a meaning that is consistent with their meaningin the context of the relevant art and will not be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Furthermore, relative terms such as “below,” “lower,” “above,” and“upper” may be used herein to describe one element's relationship toanother element as illustrated in the accompanying drawings. Suchrelative terms are intended to encompass different orientations of thedevice in addition to the orientation depicted in the accompanyingdrawings. For example, if the device in the accompanying drawings isturned over, elements described as being on the “lower” side of otherelements would then be oriented on “upper” sides of the other elements.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. Therefore, the example terms “below” and“lower” can, therefore, encompass both an orientation of above andbelow.

FIG. 1 shows an example embodiment of an insulated duct according to thepresent disclosure.

A duct 10 is operative for use in an HVAC system in order to conductforced air. Duct 10 can be effectively insulated according to at leastone building code. Such insulation minimizes air leaks. Any portionand/or component of duct 10 can be formed from a same, structurallycontinuous piece or be separately fabricated and connected. Any portionand/or component of duct 10 can be 3D printed, injection molded orformed via another manufacturing process. Any portion and/or componentof duct 10 can include metal, plastic, wood, rubber or any othermaterial, whether rigid or flexible.

Duct 10 includes an outer hollow plastic tube 11, which can be of anysize, length, width, depth, volume or any cross-section, such astriangular, circular, oval, rectangular, square, trapezoid and/or anyother geometric shape. Tube 11 can be non-plastic based as well, such asmetallic. Tube 11 can be straight, curved, wavy and/or bent. Plastic canbe biodegradable, flame-retardant and/or leak-proof. Tube 11 can have anexternal surface 15 with a white reflective portion. However, othercolors can be used as well, whether reflective or non-reflective canalso be used. Tube 11 can also have at least one aperture for use with afastener, such as a screw. In one example embodiment, tube 11 is about ⅛inch thick, about 4 feet long and has an R-value measuring insulation ofabout 2. In another example embodiment, tube 11 has a squarecross-section with each side being 12.5 inches. Tube 11 can be a pipe.

Duct 10 further includes an inner hollow plastic tube 12 inside tube 11.Tube 12 is used for conducting forced air therethrough, such as throughthe HVAC system. Tube 12 can be of any size, length, width, depth,volume or any cross-section, such as triangular, circular, oval,rectangular, square, trapezoid and/or any other geometric shape. Tube 12can be non-plastic based as well, such as metallic. Tube 12 can be canbe straight, curved, wavy and/or bent. Plastic can be biodegradable,flame-retardant and/or leak-proof. Tube 11 can be as thick as tube 12 ordiffer in thickness from tube 12. Tube 11 and tube 12 can be identicallyshaped, such as both being square, or differently shaped from eachother, such as one is circular and one is square. Tube 12 can have aninternal surface 16 with a bacteria-resistant portion. Tube 11 can havethe R-value equal to, less than or greater than tube 12. In one exampleembodiment, tube 12 is about ⅛ inch thick, about 4 feet long and has theR-value of about 0.5. In another example embodiment, tube 12 has asquare cross-section with each side being 10 inches. Tube 12 can be apipe. Tube 12 and tube 11 can be concentric with each other ornon-concentric with each other. Open ends of tubes 11 and 12 can beparallel to each other or non-parallel to each other. For example, layer13 can be slanted diagonally between the open ends of tubes 11 and 12such that the open end of tube 11 projects out further than the open endof tube 12.

Duct 10 also includes an insulating foam layer 13 enveloping tube 12.Such envelopment can be full or partial. Alternatively, layer 13 can benon-foam based. Tube 11 envelops layer 13. Such envelopment can be fullor partial. Layer 13 can have the R-value of at least about 7. However,the R-value of layer 13 can be lower as well. Layer 13 can be a sprayfoam filler. Layer 13 can include polyurethane or any equivalentthereof. In one example embodiment, layer 13 is about 1.25 inch thick,about 4 feet long and has the R-value of about 7.5. Layer 13 can becovered by a cover such that layer 13 is not visible when viewed fromthe front of duct 10.

Tube 11, tube 12 and layer 13 have a combined insulation R-value of atleast about 8. Some building codes in some jurisdictions require thatall ductwork be insulated to such insulation rating. However, otherinsulation ratings are possible as well, such as the combined insulationR-value of at most 8.

Duct 10 can include a plurality of support elements 14 spanning throughlayer 13 between tube 12 and tube 11. Elements 14 can define a pluralityof distinct channels or cavities between tube 11 and tube 12, which canbe filled with insulating material, such as foam. The channels or thecavities can fully extend between the open ends to allow for fluidcommunication. The channels or the cavities can be open or closed. Anyand/or all of such channels and/or cavities can include and/or evencontain identical and/or different insulating materials. Althoughelements 14 can include plastic, which can be biodegradable,flame-retardant and/or leak-proof, elements 14 can also include othermaterials, such as metal, wood, rubber and the like. Elements 14 canextend, whether linearly, wavy, curly and/or in any other way, alongtube 12 and/or tube 11. Elements 14 can be longer, shorter or identicalin length to tube 11 and/or tube 12. On each side of duct 10, there canbe one or more elements 14. For example, since duct 10 has a squarecross-section, any and/or all sides can have at least one element 14 andanother element 14 extending at the corner from tube 12 to tube 11. Tube11, tube 12 and/or elements 14 can be unitary, such as injected moldedor 3D printed. For example, when a mold having tube 11 connected to tube12 via elements 14 is molded, then the mold can be filled with layer 13or other insulating materials.

Duct 10 can also include a plurality of rigid, such as plastic, L-shapedcorner pieces installed onto one and/or more corners of duct 11 tosupport the square shape of tube 11. Such pieces can extend along tube11 or alternatively a plurality of such pieces can be installed onto oneand/or more corner sides. Alternatively, corner pieces can be C-shapedor U-shaped when tube is elliptical.

FIG. 2 shows another example embodiment of an insulated duct accordingto the present disclosure. Some elements of this figure are describedabove. Thus, same reference characters identify same or like componentsdescribed above and any repetitive detailed description thereof willhereinafter be omitted or simplified in order to avoid complication.

A duct 20 is operative for use in an HVAC system. Duct 20 can be curvedas illustrated. Although duct 20 can be structured similarly oridentically to duct 10, duct 10 can be different from duct 10. Anyportions and/or components of duct 20 can be formed from a same,structurally continuous piece or separately fabricated and connected.Any portion and/or component of duct 20 can be 3D printed, injectionmolded or formed via another manufacturing process. Duct 20 can besmoothly curved.

Duct 20 can include a gasket comprising of a foam layer having anadhesive on both sides for adhering to other foam layers from matingducts. The gasket creates a flush seal, which fills the space betweenthe mating ducts in order to effectively minimize air leakage from orinto the joined ducts, while conducting the forced air. The gasket canbe similar to a duct disclosed and described with reference to FIG. 3.Duct 20 can conducts the forced air, while effectively insulatingaccording to some building code and minimizing air leaks.

FIG. 3 shows an example embodiment of an intermediate duct before usewith a pair of insulated ducts according to the present disclosure. Someelements of this figure are described above. Thus, same referencecharacters identify same or like components described above and anyrepetitive detailed description thereof will hereinafter be omitted orsimplified in order to avoid complication.

A duct 30 is operative for use in an HVAC system. Any portions and/orcomponents of duct 30 can be formed from a same, structurally continuouspiece or separately fabricated and connected. Any portions and/orcomponents of duct 30 can be 3D printed, injection molded or formed viaanother manufacturing process. Any portion and/or component of duct 30can be of any size, length, width, depth, volume and/or anycross-section, such as triangular, circular, oval, rectangular, square,trapezoid and/or any other geometric shape. Any portion and/or componentof duct 30 can include metal, wood, rubber, plastic and/or othermaterials. When duct 30 includes plastic, then such plastic can bebiodegradable, flame-retardant and/or leak-proof. Any portion and/orcomponent of duct 30 can be similar or identical to duct 10 and/or duct20 or be different from duct 10 and/or duct 20. Duct 30 can function asa gasket to effectively minimize air leaks.

Duct 30 includes an outer hollow tube 31 having an interior surface 34,which can fully or partially extend between two open ends of tube 31.Although tube 31 can include plastic, tube 31 can include othermaterials, such as wood, metal, rubber and/or others. Surface 34 has apair of side regions 35, 36 and a pair of middle regions 37therebetween. Regions 35, 36 and/or regions 37 can fully extend alongsurface 34. However, regions 35, 36 and/or region 37 can also partiallyextend along surface 34. Tube 31 can have an external surface 43 with awhite reflective portion. Tube 31 can also have at least one aperturefor use with a fastener, such as a screw.

Duct 30 further includes an inner hollow tube 32 having an exteriorsurface 38, which can extend between two open ends of tube 32. Althoughtube 32 can include plastic, tube 32 can include other materials, suchas wood, metal, rubber and/or others. Surface 38 has a pair of sideareas 39, 40 and a pair of middle areas 41 therebetween. Areas 39, 40and/or areas 41 can fully extend along surface 38. However, areas 39, 40and/or areas 41 can also partially extend along surface 38. Tube 32extends along inside tube 31. Region 37 opposes area 41 and regions 35,36 oppose areas 39, 40.

Tube 32 is used for conducting forced air therethrough. Tube 32 can havean internal surface 44 with a bacteria-resistant portion. Regions 35, 36and areas 39, 40 can be adhesively coated for adhering to materials,such as plastic of other ducts. Tube 31 can have the R-value greaterthan tube 32. Alternatively, tube 31 can have the R-value lesser thantube 32.

Duct 30 also includes a foam layer 33 filled within space between tubes31 and 32. Layer 33 can partially fills such space. Layer 33 is recessedwith respect to the open ends of tube 31 and/or tube 32. Alternatively,layer 33 can be recessed only on one end of tube 31 and/or tube 32. Suchrecessing can be present on both ends of duct 30 and/or can allow foracceptance of straight or curved ducts, like ducts 10 and/or duct 20.Such recessing can be linear or diagonal, whether upwardly ordownwardly. Such recessing can also be smooth, wavy, zigzag or any otherpattern. Layer 33 partially envelops tube 32. Such partial envelopmentcan be identical on both open ends of tube 32 or different on both openends of tube 32. Tube 31 fully envelops layer 33. Enveloping can includesurrounding.

Layer 33 has portions 42 exposed to regions 35, 36, 37 and areas 39, 40,41. Portions 42 are adhesively coated for adhering to another foam layerand can create a seal to effectively reduce air leaks of the forced air.Layer 33 can include polyurethane. Layer 33 can have the R-value of atleast about 7. Alternatively, layer 33 can have the R-value of at mostof about 7. Tube 31, tube 32 and layer 33 can have a combined R-value ofat least about 8. Layer 33 can have at least one element 14, such asduct 10 or duct 20. Alternatively, layer 33 can lack any elements 14.

Duct 30 can include a plurality of support elements extending throughlayer 33 from tube 32 to tube 31, similarly to ducts 10 and/or 20. Theelements can include plastic and extend along tube 32. Tube 31, tube 32,layer 33 and the elements can be unitary. Duct 30 can conduct the forcedair, while effectively insulating according to some building code andminimizing air leaks.

FIG. 4 shows an example embodiment of a ductwork employing anintermediate duct according to the present disclosure. Some elements ofthis figure are described above. Thus, same reference charactersidentify same or like components described above and any repetitivedetailed description thereof will hereinafter be omitted or simplifiedin order to avoid complication.

A ductwork, as shown, includes ducts 10, 20 and 30 is operative for usein an HVAC system. Portions 42 are in adhesive contact with the firstlayer and the second layer 13 of ducts 10 and 20.

Tube 31 has a larger perimeter than tube 11 and of duct 10 tube 11 ofduct 20 in order to fit over tube 11 of duct 10 and tube 11 of duct 20.Tube 32 has a smaller perimeter than tube 12 of duct 10 and tube 12 ofduct 20 in order to fit into tube 12 of duct 10 and tube 12 of duct 20.Tube 12 of duct 10 is in fluid communication with tube 12 of duct 20 viatube 32. Alternatively, tube 31 and/or tube 32 has a smaller and/orlarger perimeter than tubes 11 and/or 12 of ducts 10 and/or 20.

The description of the present disclosure has been presented forpurposes of illustration and description, but is not intended to befully exhaustive and/or necessarily limited to the disclosure in theform disclosed. Many modifications and variations in techniques andstructures will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the disclosure as setforth in the claims that follow. Accordingly, such modifications andvariations are contemplated as being a part of the present disclosure.The scope of the present disclosure is defined by the claims, whichincludes known equivalents and unforeseeable equivalents at the time offiling of this application.

What is claimed is:
 1. An HVAC duct for use in an HVAC system, the ductcomprising: an outer tube having a fully continuous external perimeter;an inner tube capable of conveying forced air, the inner tube extendingwithin the outer tube and along the outer tube; a plurality of supportelements spanning between the outer tube and the inner tube, theelements extending along the inner tube and the outer tube lengthwise,the elements defining a plurality of channels between the outer tube andthe inner tube, wherein the outer tube, the inner tube and the elementsare fully unitary, wherein the channels containing a plurality ofthermally insulating layers, wherein the outer tube, the inner tube, andat least one of the layers having a combined R-value between about 8 andabout 12, wherein the outer tube having an R-value greater than theinner tube, the at least one of the layers having an R-value betweenabout 7 and about 10, the outer tube having an external surface with awhite reflective area.
 2. The duct of claim 1, wherein at least one ofthe inner tube, the outer tube, and at least one of the elementsincluding plastic, the at least one of layers including polyurethanefoam.
 3. The duct of claim 1, wherein the outer tube having asubstantially identical thickness as the inner tube, the inner tubehaving an internal surface with a bacteria-resistant area.
 4. The ductof claim 1, wherein the outer tube including at least one of a linearsection and a corner section.
 5. The duct of claim 1, wherein the outertube contains at least two sides substantially parallel to each other.6. The duct of claim 1, wherein the outer tube and the inner tube areshaped differently from each other.
 7. The duct of claim 1, wherein theouter tube and the inner tube are shaped identically to each other. 8.The duct of claim 1, wherein the outer tube having an inner corner, theinner tube having an outer corner, at least one of the elements spanningbetween the inner corner and the outer corner.
 9. The duct of claim 1,wherein the outer tube includes an external corner, the outer tubehaving a corner piece installed onto the corner, the corner piececonfigured for providing support to the outer tube.
 10. The duct ofclaim 1, wherein the inner tube is shaped for conveying the forced airabout 90 degrees from input of the forced air into the inner tube tooutput of the forced air from the inner tube.
 11. An HVAC duct for usein an HVAC system, the duct comprising: an outer tube having an interiorspace and a first open end, the outer tube having a fully continuousexternal perimeter; an inner tube capable of conveying forced air, theinner tube extending within the interior space and along the outer tube,the inner tube having a second open end in proximity of the first end; athermally insulating layer partially filling the interior space, thelayer recessed inwardly with respect to the first open end and thesecond open end, wherein the outer tube, the inner tube, and the layerhaving a combined R-value between about 8 and about 12, wherein theouter tube having an R-value greater than the inner tube, wherein thelayer having an R-value between about 7 and about 10, wherein the outertube having an external surface with a white reflective portion.
 12. Theduct of claim 11, wherein the outer tube having an interior surface, theinner tube having an exterior surface, a portion of at least one of theinterior surface and the exterior surface is adhesively coated, theportion lacking the layer thereon.
 13. The duct of claim 11, wherein thelayer is adhesively coated for adhering to another thermally insulatinglayer of another duct.
 14. The duct of claim 11, further comprising aplurality of support elements spanning between the outer tube and theinner tube, the elements extending along the inner tube and the outertube lengthwise, the elements defining a plurality of channels betweenthe outer tube and the inner tube, wherein the outer tube, the innertube and the elements are fully unitary, the channels containing thelayer.
 15. The duct of claim 11, wherein the inner tube having aninternal surface with a bacteria-resistant portion, the layer includingpolyurethane foam.
 16. The duct of claim 11, wherein the outer tubeincluding at least one of a linear section and a corner section.
 17. AnHVAC ductwork for use in an HVAC system, the ductwork comprising: afirst HVAC duct including a first outer tube and a first inner tubecapable of conveying forced air, the first outer tube having a firstfully continuos external perimeter, the first inner tube extendingwithin the first outer tube and along the first outer tube, the firstduct including a plurality of support elements spanning between thefirst outer tube and the first inner tube, the elements extending alongthe first inner tube and the first outer tube lengthwise, the elementsdefining a plurality of channels between the first outer tube and thefirst inner tube, the channels containing a plurality of thermallyinsulating layers, wherein the first outer tube, the first inner tube,and at least one of the layers having a combined R-value between about 8and about 12, wherein the outer tube having an R-value greater than thefirst inner tube, the at least one of the layers having an R-valuebetween about 7 and about 10, the first outer tube having an externalsurface with a white reflective area; a second HVAC duct including asecond outer tube having an interior space and a first open end, thesecond outer tube having a second fully continuous external perimeter,the second duct including a second inner tube capable of conveying theforced air, the second inner tube extending within the interior spaceand along the second outer tube, the second inner tube having a secondopen end in proximity of the first end, the second duct including athermally insulating layer partially filling the interior space, thelayer recessed inwardly with respect to the first open end and thesecond open end, the second outer tube wider than the first outer tube,wherein the first outer tube, the first inner tube, and the elements arefully unitary, the layers are in contact with the layer, the first innertube in fluid communication with the second inner tube, the first outertube partially within the interior space.
 18. The ductwork of claim 17,wherein the second outer tube having an interior surface, the secondinner tube having an exterior surface, a portion of at least one of theinterior surface and the exterior surface is adhesively coated, theportion lacking the layer thereon.
 19. The ductwork of claim 17, whereinthe layer is adhesively coated for adhering to the layers.
 20. Theductwork of claim 17, wherein the second outer tube, the second innertube, and the layer having a combined R-value between about 8 and about12, the second outer tube containing an aperture configured for use witha fasterner.
 21. The ductwork of claim 17, wherein the first ductincluding at least one of a linear section and a corner section.